Electrical switching devices



Aug. 26, 1958 H. D. GAITE ELECTRICAL SWITCHING DEVICES Filed April 26. 1954 Pm. Z

1mm 2mm Mwad M W W United States Patent ELECTRICAL SWITCHING DEVICES Harold D. Gaite, Taplow, England, assignor to British Telecommunications Research Limited, Taplow, England, a British company Application April 26, 1954, Serial No. 425,515

Claims priority, application Great Britain April 28, 1953 3 Claims. (Cl. 200-105) The present invention relates to electrical switching devices and is more particularly concerned with devices for selectively completing different electrical circuits, for instance in response to the step-by-step operation of a control member which is driven by electro-magnetic pawl-and-ratchet gear. The invention moreover contemplates the simultaneous completion of a number of circuits in any one position, conveniently on a selective basis so that the device can be used for the generation of code signals.

In the design of such devices it is often important that no appreciable wear shall take place after a very large number of operations so that reliable contact can still be attained. Moreover it is often required that the code produced by the connection of potential to certain combinations of signalling leads connected to the switch shall be capable of ready alteration. It is also generally convenient that the device shall be compact in size and economical to manufacture. The present invention meets all these requirements in a very satisfactory manner.

According to the invention on electrical switching device for controlling a plurality of circuits simultaneously comprises a rotatable disc provided with a plurality of groups of depressions arranged for the selective accommodation of metallic balls, the balls corresponding to each group of depressions being adapted to cooperate with a plurality of contact fingers arranged to project through holes in a protective cover which serves to retain the balls in position.

The invention will be better understood from the following description of a preferred form of carrying it into effect which should be taken in conjunction with the accompanying drawings comprising Figs. 1 to 3. Of these Fig. 1 represents a plan view with a portion of the protecting cover broken away, Fig. 2 is a similar view with the protecting cover and rotatable disc removed, and Fig. 3 is a vertical section through the axis of rotation of the disc.

The device illustrated is very suitable for generating codes as used in teleprinter operation for which purpose it was particularly designed.

The various elements are mounted on a channelshaped metallic base 1 which is attached to an insulating block 2 serving for the mounting of the various tags and terminals for making the electrical connections. This block is provided with two locating and supporting pins 3 and a number of floating metallic members such as 4 which form soldering tags at the inner end and at the outer end form knife contacts for co-operating with corresponding spring contacts on the supporting equipment when the unit is plugged into position.

The driving electromagnet is provided with a coil 5 which is mounted on a core 6 secured to a heel-piece 7 by means of screw 8 secured to the base plate. The magnet controls an armature 9 which is shaped as shown more particularly in Fig. 2 and is pivoted about the pin 10 which projects through the base 1 and serves for the location of the heel-piece 7 to which it is secured by "ice the bracket 11 and screws 12. The armature carries a pawl 13 which is pivoted at 14 and subject to the action of a spring 15. The upturned projection 15 on the armature 9 forms a front or over-run stop for the pawl and the screw 16 forms a backstop for the armature.

The rotatable disc is mounted on a fixed shaft 17 and actually consists of two discs, one of which 18 is perforated with a number of groups of radial holes and the other 19 is an unperforated plane disc. The holes forming a group need not be radial provided the tips of the contact fingers are arranged similarly and it may be more convenient to stagger them. The rotating assembly also includes a ratchet wheeel 20 arranged to co-operate with the pawl and also subject to the action of a detent spring 21. In addition the assembly includes an insulating disc 22 which as shown is provided with two diametrically opposite projections 23 and 24 arranged to operate changeover contact springs 25 in the corresponding positions of the disc. Various other configurations for the disc 22 could be used to give other switching efiects and control the-end of different cycles. As an alternative the contacts 25 might co-operate with interrupter contacts on the magnet to give a homing operation in certain circumstances. Generally however the magnet vwill be controlled from the teleprinter mechanism so as to be advanced one step at suitable intervals, for instance at the end of each character. I

Metallic balls 26 are provided in selected holes round the disc so as to permit potential connected to the disc to be selectively applied to one or more of a group of five conductors. The disc with its group of balls is covered by a protecting member 27, preferably of transparent plastic, which is secured in place by means of the four screws 28 engaging in pillars mounted on the base. The pillars 29 and 30 adjacent the magnet are preferably of metal while the pillars 31 and 32 at the end of the device are conveniently of insulating material and serve for the support of the switching springs 25.

The protective cover 27 also provides a mounting for the five contact fingers 33 which are so located as to engage with one or more of the balls which are provided in the different radial positions as the disc is rotated. These contact fingers comprise wires with turned-over ends which project through holes in the protective cover so as to engage with the balls. A stop 34 is provided to prevent a wire which does not engage a ball from passing through the plate sufiiciently to contact the disc. The wires are held in position in a block 35 by means of screws 36, this block being riveted to the protective cover.

The cover 27 is provided with a detachable window 37 of the same material which is secured by bolts 38 and when removed exposes one radial row of holes. This arrangement facilitates the location of the balls in the appropriate holes. It will be appreciated that a switching device of this type permits the alteration of the codes as desired with the minimum of trouble. It will be understood that though it is preferable that the cover 27 should be of insulating material, use could also be made of a metallic cover in conjunction with a suitable insulating plate and/or bushes.

The device as a whole is preferably protected by a slide-on metallic cover (not shown) of the type usual for electrical equipment of this class and this will conveniently be provided with a handle for easy manipulation.

It should be mentioned that though the invention has been described in connection with a rotary switching de vice which is electromagnetically operated in a step-bystep manner, this arrangement is not essential and the disc could if desired be driven continuously by an electric motor or by any other suitable drive. Moreover though the arrangement according to the invention possesses particular advantages for telecommunication purposes, particularly in connection with teleprinters, the general principle of operation is capable of much wider application, for instance to the control of advertising signs, luminous indicators and the like.

I claim:

1. An electrical switching device for controlling a i plurality of circuits simultaneously comprising a rotatable disc, a plurality of groups of depressions located on said disc, the depressions of each group being located at different radial distances from the axis of rotation of said disc, which distances are the same for all the groups, a plurality of metallic balls selectively located in said depressions in accordance with the desired switching operations, an insulating protective cover for retaining said balls in position, a plurality of contact fingers projecting through said cover at radial distances corresponding to the various depressions of a group, said cover having a removable portion opening to one group of said depressions so as to facilitate selective placing of the balls in said depressions, and means for effecting continuous step-by-step rotation of said disc.

2. A switching device as claimed in claim 1 in which the rotation of said disc is effected by pawl and ratchet mechanism driven by an electromagnet which is also arranged to operate contacts which interrupt its own circuit.

3. A switching device as claimed in claim 1 in which the disc has secured to it a cam which is arranged to operate contact springs in predetermined positions.

References Cited in the file of this patent UNITED STATES PATENTS 746,998 Schmidt Dec. 15, 1903 1,097,455 Marshall May 19, 1914 1,410,855. Veneria Mar. 28, 1922 1,714,680 Levinson May 28, 1929 2,209,084 Foster July 23, 1940 2,267,102 Huggins Dec. 23, 1941 2,406,028 Myers Aug. 20, 1946 2,428,569 Hunt Oct. 7, 1947' 2,431,381 Elliott Nov. 25, 1947 2,695,379 Myers et al. Nov. 23, 1954 FOREIGN PATENTS 701,572 France Jan. 12, 1931 

